         {g2 :game s1 :settlement} (create-settlement g1 "name" {:x 15 :y 18} (.id gr1) 11)
         {g3 :game gr2 :group} (create-tribe g2 "name" {:x 15 :y 18} (Population. 0 0 0 0 0) initial-culture initial-society)
         {g4 :game s2 :settlement} (create-settlement g3 "name" {:x 15 :y 18} (.id gr2) 12)]
-    (is (= false (ghost-city? g2 (.id s1))))
-    (is (= true (ghost-city? g4 (.id s2))))))
+    (is (false? (ghost-city? g2 (.id s1))))
+    (is (true? (ghost-city? g4 (.id s2))))))
 
 (deftest test-n-groups-alive
   (let [g0 (create-game nil)
         g1 (:game (create-tribe g0 "name" {:x 15 :y 18} (Population. 1 2 3 4 5) initial-culture initial-society))
         g2 (:game (create-tribe g1 "name" {:x 15 :y 18} (Population. 0 0 0 0 0) initial-culture initial-society))]
-    (is (= 0 (n-groups-alive g0)))
+    (is (zero? (n-groups-alive g0)))
     (is (= 1 (n-groups-alive g1)))
     (is (= 1 (n-groups-alive g2)))))
 

      (is (= initial-society (society ga gr))))))

(deftest test-dead?
  (is (= false (dead? (Group. nil nil nil (Population. 1 2 3 4 5) nil))))
  (is (= true  (dead? (Group. nil nil nil (Population. 0 0 0 0 0) nil)))))

(deftest test-alive?
  (is (= true  (alive?  (Group. nil nil nil (Population. 1 2 3 4 5) nil))))
  (is (= false (alive?  (Group. nil nil nil (Population. 0 0 0 0 0) nil)))))

(deftest test-know?
  (consider-base-group

(deftest test-get-language
  (consider-base-group
    (fn [ga gr]
      (is (nil? (get-language ga gr))))))

(deftest test-assoc-language
  (consider-base-group
